Hardness and fracture toughness of ultra-rine WG-10Co-X cemented carbides prepared from nanocrystalline powders

Abstract

Microstructure and mechanical properties of ultra-fine WC-10Co-X cemented carbides were investigated. Nanocrystalline WC-10Co-X powders with an average WC size of 100 nm were prepared by spray drying of solution containing ammonium metatungstate and cobalt nitrate. Varying amounts of TaC, Cr3C2 and VC were added into ultrafine WC-10Co cemented carbides as grain growth inhibitors. The hardness of WC-10Co cemented carbides increased with decreasing WC grain size following the Hall-Petch-type relationship. The fracture toughness of ultra-fine WC-10Co fabricated by the spray conversion process was lower than that of conventional WC-10Co. These differences in fracture toughness arose from solute content in the Co binder phase. The fracture toughness of WC-10Co-X cemented carbides with the same solute content in the Co binder phase varied with WC grain size and Co mean free path.